Spray foam insulation gun

ABSTRACT

An apparatus is provided for the mixing of a first liquid foaming agent component with compressed air in a mixing chamber to produce a foam. A nozzle for ejecting a second liquid component into the foam is provided downstream of the mixing chamber. The mixing chamber is attached to the downstream side of a valve housing. The valve housing includes a triple plug valve for simultaneously selectively connecting and disconnecting a first liquid component inlet and an air inlet with the mixing chamber and a second liquid component inlet with the nozzle. First port means, connecting the air inlet downstream of the triple plug valve, to a plurality of air ejection orifices communicating with the mixing chamber is provided within the valve housing. Air control valve means is provided within said first port means for controlling the amount of air flowing to said mixing chamber. Second port means is provided, within said valve housing, for communicating the air inlet port upstream of said triple plug valve with a fluid passage for the second liquid component at a point downstream of said triple plug valve, to provide purge air to the nozzle. A second valve means is provided in said second port means for controlling the flow of purge air to the nozzle.

RELATED APPLICATION

This application is a continuation-in-part of my prior U.S. applicationSer. No. 901,245 filed Apr. 28, 1978, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to apparatus for mixing and sprayingfoam insulation and more particularly, but not by way of limitation, tosuch apparatus having purge air systems for cleaning of the passagewayssubsequent to the mixing of the foam components.

2. Description of the Prior Art

The prior art includes numerous devices for the mixing and applicationof foam insulation. Such apparatus generally include a mixing chamberwherein a first liquid component is mixed with compressed air, and anozzle downstream of the mixing chamber whereby a second liquidcomponent is ejected into the mixture of the first component and air.Most of those devices are, however, of a very bulky complex designincluding much external tubing.

The present invention provides a compact efficient apparatus for themixing of components for foam insulation and also provides simple andefficient means for the cleaning of the apparatus by purging theorifices of the nozzle with air after the mixing operation.

SUMMARY OF THE INVENTION

An apparatus is provided for the mixing of a first liquid foaming agentcomponent with compressed air in a mixing chamber to produce a foam. Anozzle for ejecting a second liquid component into the foam is provideddownstream of the mixing chamber. The mixing chamber is attached to thedownstream side of a valve housing. The valve housing includes a tripleplug valve for simultaneously selectively connecting and disconnecting afirst liquid component inlet and an air inlet with the mixing chamberand a second liquid component inlet with the nozzle. First port means,connecting the air downstream of the triple plug valve, to a pluralityof air mix orifices communicating with the mixing chamber is providedwithin the valve housing. Air control valve means is provided withinsaid first port means for controlling the amount of air flowing to saidmixing chamber. Second port means is provided, within said valvehousing, for communicating the air inlet port upstream of said tripleplug valve with a fluid passage for the second liquid component at apoint downstream of said triple plug valve, to provide purge air to thenozzle. A second valve means is provided in said second port means forcontrolling the flow of purge air to the nozzle.

It is therefore a general object of the present invention to provide anapparatus for the mixing of foam insulation for spraying upon a surface.

A further object of the present invention is to provide a spray foammixing apparatus having means for purging the apparatus with air toprevent the fluid components from setting up inside the apparatus.

Another object of the present invention is the provision of a spray foaminsulation apparatus providing a superior mixture of the liquidcomponents so as to provide the desired homogenous distribution of thecomponents within the foam to create a structurally sound foam body.

Yet another object of the present invention is the provision of a lightweight compact easily manufactured, operated and serviced spray foaminsulation gun.

Other and further objects, features and advantages of the presentinvention will be apparent to those skilled in the art upon a reading ofthe description of preferred embodiments which follows when taken inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional partially cut-away view of the foam insulationspray gun of the present invention.

FIG. 2 is a rear view of the apparatus of FIG. 1.

FIG. 3 is a frontal view of the valve housing of FIG. 1 showing portionsof the internal porting of the valve housing in dashed lines.

FIG. 4 is a lengthwise view of the triple plug valve.

FIG. 5 is a second view of the triple plug valve of FIG. 4 rotatedthrough an angle of 90° about its central axis.

FIG. 6 is a top view of that portion of the valve housing which receivesthe triple plug valve, and shows the stop bars which limit therotational position of the triple plug valve within the valve housing.

FIG. 7 is a partially cut-away view of an alternative embodiment havingan integral mixing chamber and forward nipple portion. Also variousinternal porting of the valve housing is shown in dashed lines.

FIG. 8 is a sectional view of the valve housing of the spray gun of FIG.1, with the triple plug valve in the closed position.

FIG. 9 is a sectionally partially cut-away view of another alternativeembodiment of the present invention having an annular spray nozzle andhaving a deflector shield over the foaming agent outlet.

FIG. 10 is a frontal view of the valve housing of FIG. 9 showing thedeflector shield.

FIG. 11 is an elevation view of the spray nozzle insert of theembodiment of FIG. 9.

FIG. 12 is bottom view of the spray nozzle insert of FIG. 11.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

Referring now to the drawings, and particularly to FIG. 1, the foaminsulation spray gun of the present invention is shown and generallydesignated by the numeral 10. The spray gun 10 includes a valve housing12 with a mixing chamber 14 attached to the front side of the valvehousing.

In the following description the terms "upstream" and "downstream" areoften used to define the orientation of one component of the spray gun10 to another component. This, of course, refers to the direction offlow of the various fluids through the spray gun 10. The fluids firstenter the valve housing 12, flow through various porting and valveswithin the valve housing and then into the mixing chamber 14 or to thenozzle 94. Thus, the mixing chamber 14 is said to be downstream of thevalve housing 12, and the nozzle 94 is said to be downstream of themixing chamber 14.

The valve housing 12 is comprised of a substantially rectangularparallelepiped nylon block. Disposed therethrough is a transverse plugvalve bore 16, within which is rotatingly received a triple plug valvegenerally designated by the numeral 18. /

The valve housing 12 has longitudinally disposed therein threesubstantially parallel inlet bores 20, 22 and 24. These are the foamingagent inlet bore, the resin inlet bore and the compressed air inletbore, respectively. The longitudinal inlet bores 20, 22 and 24 eachcommunicate with rear end surface 26 of the valve housing 12 andintersect the transverse plug valve bore 16.

With respect to the components comprising the final foam mixture, thefoaming agent and resin solution may be referred to as first and secondfluid or liquid components, and the compressed air may be referred to asa gaseous component.

The triple plug valve 18 comprises a means for simultaneouslyselectively connecting and disconnecting the foaming agent inlet bore 20and the compressed air inlet bore 24 to the mixing chamber 14, and theresin solution inlet bore 22 to the nozzle 94.

The longitudinal bore 20 includes a threaded foaming agent inlet 28. Thebore 20 also includes a threaded foaming agent outlet 30 communicatingwith the interior of the mixing chamber 14. Threadedly received withinthe foaming agent outlet 30 is a metering insert 32 having a foamingagent orifice 34 disposed therein.

The longitudinal bore 22 includes a threaded resin inlet 36 at one endthereof communicating with the rear surface 26 of the valve housing 12.At the other end of the bore 22 is a threaded resin outlet 38.Threadedly received within the outlet 38 is a longitudinally extendingresin tube 40 which is concentric with and located along thelongitudinal axis of the mixing chamber 14.

The longitudinal bore 24 includes a threaded compressed air inlet 42 aton end thereof. The second end 44 of the compressed air bore 24 is ablind end.

Referring now to FIGS. 3 and 7, various internal porting of the valvehousing 12 is shown in dashed lines. Mounted within the valve housing 12is an air control valve 46 and a resin-air purge valve 48. Each of thevalves 46 and 48 includes a conical valve member 49 which seats upon ashoulder 51 machined into the valve housing 12.

A first internal port 50 communicates between a portion of thecompressed air bore 24 downstream of the triple plug valve 18, as isbest seen in FIG. 7, and the upstream side of the air control valve 46,as is best seen in FIG. 3. The downstream side of the air control valve46 communicates with a transverse blind port 54 which has three airejection orifices 56, 58 and 60 communicating with the transverse blindport 54 and the front surface 62 of the valve housing 12 closelyadjacent the foaming agent outlet 30.

Each of the three air ejection orifices 56, 58 and 60 is oriented sothat an imaginary extension of its central axis intersects an imaginaryforward extension of the longitudinal or central axis of the foamingagent orifice 34. Also, the air ejection orifices 56, 58 and 60 are notparallel to each other and they therefore intersect with the axis of thefoaming agent orifice 34 at three different angles. This causes the jetsof compressed air emitted from the air ejection orifices to impinge uponthe jet of foaming agent emitted from the foaming agent orifice 34 at avariety of angles thereby contributing to the turbulence in the mixingchamber 14 to assure adequate foaming of the foaming agent.

To aid the agitation and turbulent mixture of the foaming agent andcompressed air within the mixing chamber 14 it is desirable that theinterior of the mixing chamber 14 be packed with a porous fillermaterial 61. The filler material 61 is preferably comprised of brasswire scouring pads such as are used for domestic cleaning or a pluralityof glass beads.

A second internal port 63 communicates between a portion of thecompressed air bore 24 upstream of the triple plug valve 18, as bestseen in FIG. 7, and the upstream side of the resin air purge valve 48,as best seen in FIG. 3. The downstream side of the resin air purge valve48 communicates with the resin bore 22 and resin outlet 38, by means ofthe third internal port 65. In this manner, compressed air may bedirected to the resin line to purge it after the triple plug valve 18 isclosed. This is due to the fact that the purge air is taken by internalport 63 from upstream of the triple plug valve 18, as seen in FIG. 7.

Also communicating with the compressed air bore 24, and in substantiallythe same plane as the first port 50, is a drilling cavity 64 whichcommunicates with an external surface of the valve housing 12. Thedrilling cavity 64 provides means for a drill to be inserted to drillout the first internal port 50. After drilling of the port 50, thedrilling cavity 64 is plugged with a brass plug 66.

The front surface 62 of the valve housing 12 further includes a discshaped recess 72 which is concentric with and receives the mixingchamber 14. On opposite sides of the recess 72, as viewed in FIG. 3, aretwo threaded holes 74 by means of which retaining clips 75, which fitover the shoulder 76 of the mixing chamber 14, may be fastened to thevalve body 12 to retain the mixing chamber 14 in place upon the valvebody 12.

The mixing chamber 14 includes a cylindrical outer body 78 having at itsrear end the shoulder 76 for engagement with the valve housing 12 aspreviously described. The shoulder 76 includes therein an annular groove80 within which is received a resilient O-ring seal 82. The cylindricalouter body 78 is preferably constructed of a transparent material sothat the mixing action within the mixing chamber 14 may be observed.This allows any malfunction to be quickly detected.

The forward portion of the cylindrical body 78 of the mixing chamber 14,as viewed in FIG. 1, includes a truncated conical shoulder portion 84and a smaller cylindrical forward extending portion 86. Along theinternal surface of the mixing chamber 14 where the conical shoulderportion 84 meets the cylindrical forward extension 86 there is a flatannular surface 88. Concentrically and closely received within theinternal portion of the forward extending portion 86 is a brass nipple90. The brass nipple 90 includes a radially outward extending flange 92which seats upon the shoulder 88. The brass nipple 90 is press fitwithin the cylindrical extension 86 and may also be retained therein byan adhesive placed between the nipple 90 and the cylindrical extension86 if necessary.

An alternative embodiment of the forward portion of the mixing chamber14 is illustrated in FIG. 7. There the brass nipple has been deleted andreplaced by an elongated forward cylindrical extension 86a, which isconstructed integrally with the mixing chamber 14.

Concentrically inner of and radially spaced from the brass nipple 90 isthe resin tube 40. Threadedly engaging the forward end of the resin tube40 is the resin nozzle 94. The nozzle 94 includes a plurality of radialangularly extending resin orifices 96. Preferably six orifices 96,radially spaced at angles of 60° are provided. In the embodiment of FIG.1, the nipple 90 terminates adjacent the resin ejection orifices 96. Inthe embodiment of FIG. 7, the cylindrical extension 86a extendsdownstream past the resin ejection orifices 96.

The foam formed by the agitated mixing of the foaming agent andcompressed air within the mixing chamber 14 exits the spray foaminsulation gun 10 in an annular stream through the annular space betweenthe nipple 90 and the nozzle 94, thereby surrounding the nozzle 94. Thefoam is then flowing approximately parallel to the longitudinal axis ofthe apparatus.

The foam mixture is said to be axial flowing in that each of the foamparticles are flowing in a direction substantially parallel to a centrallongitudinal axis of the annular stream of foam, as opposed to exitingthe annular space in a swirling fashion. As the foam exits theinsulation gun 10 the resin solution is ejected into the foam throughthe resin orifices 96, so as to angularly impinge upon an internalportion of said annular stream, so that a turbulent mixture of foam andresin solution is produced downstream of the orifices 96.

It is necessary that the resin solution be thoroughly mixed with thefoam so as to provide a homogeneous distribution of resin throughout thecellular structure of the foam. It is this mixture of the resin solutionwith the foam which causes the foam to harden and retain its cellularstructure. If the resin solution is not thoroughly mixed with the foam,that portion of the foam unaffected by the resin will not properlyharden and the cellular structure will deteriorate as the foam dries outthereby destroying the desired insulating property of the foam.

To assure a thorough mixing of the resin solution with the foam, theresin orifices 96 are oriented at an angle of 45° with the longitudinalaxis of the spray foam insulation gun 10. The jets of resin solutionemitted from the orifices 96 then impinge upon the annular stream offoam exiting the insulation gun at a 45° angle thereby creating aturbulent mixture of foam and resin solution. In its preferred mode ofoperation, a hose 97 is closely fitted about the external surface of thenipple 90 so that the foam insulation may be more easily directed to thesurface to which it is to be applied by means of the hose 97. The actualmixing of the resin solution with the foam then takes place outside theinsulation gun 10, and preferably within the hose 97.

It is important that this mixing take place outside the insulation gun10, because of the catalyst effect of the resin solution upon the foamwhich causes it to harden almost immediately after being mixed with theresin solution. This feature, along with the purge air system, theoperation of which is described in more detail below, allows theinsulation gun 10 to be operated repeatedly over long intervals withoutthe need for disassembly and cleaning of the insulation gun 10.

The nozzle 94 has disposed therein an internal longitudinal blind bore98 which has a first counterbore 100. A resin metering insert 102 with aresin metering orifice 104 is concentrically and closely received withinthe counterbore 100. A threaded portion 106 of the counterbore 100threadedly engages the forward end of the resin tube 40 in such a mannerthat the end of the resin tube 40 engages the resin metering insert 102and clamps it against the shoulder formed between the bore 98 and thecounterbore 100 thereby holding the insert 102 in place.

The bore 98 also communicates with the resin orifices 96 whereby resinmay travel from the inlet 36, through the bore 22, the outlet 38, theresin tube 40, the resin metering orifice 104, the bore 98 and out theresin orifices 96.

Referring now to FIGS. 4 and 5, the triple plug valve 18 comprises acylindrical shaft 108 having disposed therethrough three parallel bores110, 112 and 114 which are coincident with the bores 20, 22 and 24 whenthe triple plug valve 18 is in place within the valve housing 12 and isin the open position illustrated in FIG. 1. The bores 110, 112 and 114are substantially perpendicular to the central axis of the shaft 108.

Beginning at the lower portion of the valve 18 as viewed in FIG. 4, thecylindrical portion 108 includes a first annular key retaining groove116 which receives the keeper key 118 as is seen in FIG. 1. Successivelyspaced from the annular key retaining groove 116 are annular resilientseal grooves 120, 122, 124, 126, 128 and 130.

The resilient seal grooves 120 and 122 are disposed one on either sideof the bore 114. Similarly, grooves 124 and 126 are disposed on eitherside of the bore 112 and grooves 128 and 130 are disposed on either sideof the bore 110. Each of the grooves 120 through 130 receives aresilient O-ring 131. Note that in this manner, a double seal, e.g., theseals 131 retained within grooves 122 and 124, is provided betweenadjacent bores, e.g., the bores 112 and 114. This provides a double sealagainst that possibility of premature mixing of the fluids contained inthe bores 112 and 114. Similarly a double seal is provided between bores110 and 112.

The upper end of the cylindrical shaft 108 of the triple plug valve 18,as viewed in FIGS. 4 and 5, is of greater diameter than that portionlocated below the groove 130 thereby forming a shoulder 132 adjacent thegroove 130. The shoulder 132 engages an outer surface of the valvehousing 12 to limit inward positioning of the triple plug valve 18within the valve housing 12 as is best seen in FIG. 1.

A fourth bore, 134, parallel to the bores 110, 112 and 114, is locatedin the upper portion of the cylindrical shaft 108 and receives therein avalve handle 136.

Located between the handle 136 and the shoulder 132 is a radiallyextending stop pin 138. Extending outwardly from the valve housing 12are a pair of stop bars 140 and 141, which are located one on eitherside of the stop pin 138 so as to limit the angular rotation of thetriple plug valve 18 to a 90° rotation.

This is best seen in FIG. 6.

Located on the peripheral surface of the shaft 108, about axessubstantially perpendicular to the bores 110, 112 and 114, and to thecentral axis of the shaft 108, are substantially circular sealinggrooves 142, 144 and 146, respectively. Each of the sealing grooves isconstructed so as to receive therein a resilient O-ring 147, as is bestseen in FIG. 8 where the triple plug valve 18 is shown in the closedposition.

On the opposite side of each of the bores 110, 112 and 114, from thesealing grooves 142, 144 and 146, are bleed orifices 148, 150 and 152,respectively. The bleed orifices 148, 150 and 152 are oriented to be inpartial communication with the downstream portion of the bores 20, 22and 24, respectively, when the triple plug valve 18 is in the closedposition as illustrated in FIG. 6.

To assemble the plug valve 18 within the valve housing 12, resilientseal means 131 are placed in each of the annular grooves 120, 122, 124,126, 128 and 130. Additionally, resilient O-rings 147 are placed in eachof the sealing grooves 142, 144 and 146. The triple plug valve 18 isthen inserted within the bore 16 of the valve housing 12 and is closelyreceived therein. When the triple plug valve 18 is fully inserted, theshoulder 132 abuts the outer surface of the valve housing 12 and thekeeper key 118 is placed within the annular key retaining groove 116 toretain the triple plug valve in place within the valve housing 12.

The triple plug valve is located so that the stop pin 138 is locatedbetween the stop bars 140 and 141, as seen in FIG. 6. When the tripleplug valve 113 is in the open position as seen in FIG. 1 with the bores110, 112 and 114 aligned with the bores 20, 22 and 24, respectively, thestop pin 138 is in engagement with the stop bar 140. To move the valve118 to the closed position, the valve is rotated through an angle of 90°clockwise, as seen in FIG. 6, to the position shown in FIG. 6 where thestop pin 138 engages the stop bar 141. In this position, the sealinggrooves 142, 144 and 146 circumferentially engage the bores 20, 22 and24 adjacent the inlets 28, 36 and 42, respectively. The resilientO-rings 147 disposed in the sealing grooves 142, 144 and 146 serve toprevent leakage of the fluids into the valve housing when the valve isin the closed position.

Another alternative embodiment of the insulation spray gun of thepresent invention is shown in FIGS. 9-12, and is generally designated bythe numeral 200. Spray gun 200 differs from spray gun 10 of FIG. 7 inthat spray gun 200 includes a deflector shield 202 over foaming agentoutlet 30 and includes an adjustable resin nozzle 204.

Deflector shield 202 is best shown in FIG. 10 and is an arcuate platehaving a first end 206 attached to front surface 62 of valve housing 12by a screw 208. First end 206 is substantially flat and coextensive withflat surface 62.

There is a bend 210 in deflector shield 202 near first end 206, and anapproximately 180° arcuate portiion of deflector shield 202 between bend210 and a second end 212 is formed in a spiral-like manner asillustrated in FIG. 9.

Deflector shield 202 imparts an initial swirling motion to the foammixture to insure that the mixing chamber 14 is completely filled. Thisprevents the foam mixture from creating a short circuit path betweenfoaming agent outlet 30 and the elongated forward extension 86a ofcylindrical body 74 through the porous filler material 61. The fillermaterial 61, however, breaks up the swirling motion so that asubstantially homogeneous axially flowing annular stream of foam mixtureexits forward extension 86a.

The adjustable resin nozzle 204 includes a nozzle body 214 and a spraynozzle insert 216. Nozzle body 214 is threadedly connected to resin tube40 so as to hold resin metering insert 102 in place. Nozzle body 214 hasa threaded central bore 218 in which spray nozzle insert 216 isthreadedly received.

Elevation and bottom views of spray nozzle insert 216 are shown in FIGS.11 and 12, respectively. Insert 216 is machined from a cylindrical brassbar and includes a forward end 220 and a rear end 222.

A reduced outer diameter portion 224 has tapered annular shoulders 226and 228 at the ends thereof. Shoulders 226 and 228 are inclined at 30°angles to the longitudinal axis of insert 216.

Upper end 220 includes a slot 230 for receiving a screwdriver to adjustthe position of insert 216 within nozzle body 214.

Two milled flats 232 and 234 connect annular shoulder 226 with rear end222. When insert 216 is in place within nozzle body 214 as shown in FIG.9, the resin from resin tube 40 flows past flats 232 and 234 into anannular space 236 between nozzle body 214 and reduced diameter portion224 and then exits in an annular spray between tapered shoulder 228 andthe forward end 238 of nozzle body 214. The annular spray exits at anangle of approximately 30°.

OPERATION

The spray foam insulation gun 10 is used in the following manner toproduce foam insulation and deposit the foam in place within a structureto be insulated, such as within the walls of a building. This operationis best explained with reference to FIG. 2.

The insulation gun 10 is preferably rotated 90° clockwise from theposition shown in FIG. 2 and is attached to the belt of a workman bymeans of the belt clip 154 attached to the valve housing 12.Conventional supply lines for the foaming agent, resin and air arehooked to the threaded inlets 28, 36 and 42, respectively. A hose 97 isattached to the front end of the insulation gun 10, as shown in FIG. 1,and the workman uses the hose 97 to direct the foam-resin mixture to thedesired location.

Prior to starting the foaming operation the triple plug valve 18 ismoved to the closed position and the supply lines to the inlets 28, 36and 42 are opened thereby providing pressurized foaming agent, resin andair to those inlets. The purge valve 48 is closed and the air controlvalve 46 is opened to an intermediate position.

To start the foaming operation the triple plug valve 18 is turned to theopen position thereby allowing the foaming agent and air to flow to themixing chamber 14 and allowing resin to flow to the nozzle 94 where itis mixed with the foam. The foam resin mixture is then transferred tothe desired location by means of the hose 97.

To achieve the desired foaming within the mixing chamber 14 the air flowthereto is adjusted by means of the air control valve 46.

When the foaming operation is ended the triple plug valve 18 is closedand the purge valve 48 is immediately opened to direct compressed airthrough the resin tube and out the resin orifices 96 of the nozzle 94 toclear them of any foam-resin mixture before it has time to harden andclog the resin metering orifice 104 and the resin orifices 96.

It will be appreciated that in this manner the foam insulation spray gun10 may be used repeatedly without having to be disassembled for cleaningof the orifices. Also the purge air serves to clear the foam-resinmixture from the hose 97 before it has time to harden inside the hose.

Thus, the foam insulation spray gun of the present invention is welladapted to carry out the objects and attain the ends and advantagesmentioned as well as those inherent therein. While presently preferredembodiments of the invention have been described for the purpose of thisdisclosure, numerous changes in the construction and arrangement ofparts can be made by those skilled in the art, which changes areencompassed within the spirit of this invention as defined by theappended claims.

What is claimed is:
 1. A spray foam insulation gun, comprising:a valvehousing, having first, second and third substantially parallel inletbores disposed therein for connection to supplies of foaming agent,resin and compressed air, respectively, and having a valve bore,disposed therethrough, transverse to and intersecting said inlet bores;a mixing chamber, connected to said valve housing, for mixing saidfoaming agent and compressed air to form a foaming agent-compressed airmixture; a resin nozzle, located downstream of said mixing chamber, forejecting resin into said foaming agent-compressed air mixture; firstvalve means disposed in said valve bore of said valve housing forselectively connecting and disconnecting said first and third inletbores to said mixing chamber, and said second inlet bore to said resinnozzle; port means, communicating said third inlet bore, downstream ofsaid first valve means, with said mixing chamber; a foaming agent outletcommunicating said first inlet bore with said mixing chamber; and meansfor communicating said second inlet bore with said resin nozzle.
 2. Thespray foam insulation gun of claim 1, further comprising:second valvemeans, engaging said port means, for controlling the flow of air to saidmixing chamber.
 3. The spray foam insulation gun of claim 2,wherein:said port means further comprises an air ejection orificecommunicating with said mixing chamber adjacent said foaming agentoutlet.
 4. The spray foam insulation gun of claim 3, furthercomprising:a deflector shield located downstream of said foaming agentoutlet and said air ejection orifice to deflect said foamingagent-compressed air mixture.
 5. The spray foam insulation gun of claim4, wherein:said deflector shield is further characterized as being anarcuate spiral shaped shield means for initially directing said foamingagent-compressed air mixture is a spiral flow through said mixingchamber.
 6. The spray foam insulation gun of claim 3, furthercomprising:a foaming agent orifice disposed in said foaming agentoutlet; and wherein said air ejection orifice is oriented so that astream of air emitted from said air ejection orifice will impinge upon astream of foaming agent emitted from said foaming agent orifice.
 7. Thespray foam insulation gun of claim 6, further comprising:a second airejection orifice, oriented non-parallel to said first air ejectionorifice.
 8. The spray foam insulation gun of claim 3 wherein said portmeans further comprises:a first port, communicating said third inletbore with said second valve means; and a second port, communicating saidsecond valve means with said air ejection orifice, said first and secondports being disposed within said valve housing in a plane substantiallyperpendicular to said inlet bores.
 9. The spray foam insulation gun ofclaim 8 further comprising:a drilling cavity, communicating said thirdinlet bore with an external surface of said valve housing, said drillingcavity being disposed within substantially the same plane as said firstand second ports, so that said first port can be drilled into said valvehousing; and plug means, disposed in said drilling cavity for closingsaid cavity after said first port has been drilled.
 10. The spray foaminsulation gun of claim 8, further comprising:purge valve means; a thirdport disposed within said valve housing, communicating said third inletbore, upstream of said first valve means, with said purge valve means;and a fourth port disposed within said valve housing, communicating saidpurge valve means with said second inlet bore, downstream of said firstvalve means, whereby the flow of air to said second inlet bore may becontrolled by said purge valve means.
 11. The spray foam insulation gunof claim 1, further comprising:port means, communicating said thirdinlet bore, upstream of said first valve means, with said second inletbore, downstream of said first valve means; and purge valve means,engaging said port means for controlling the flow of air to said secondinlet bore.
 12. The spray foam insulation gun of claim 11, wherein saidport means further comprises:a first port disposed within said valvehousing, communicating said third inlet bore with said purge valvemeans; and a second port disposed within said valve housing,communicating said purge valve means with said second inlet bore. 13.The spray foam insulation gun of claim 1, wherein:said means forcommunicating said second inlet bore with said resin nozzle is a tubelocated within said mixing chamber.
 14. The spray foam insulation gun ofclaim 13, further comprising:a resin metering orifice, communicatingsaid resin tube with said resin nozzle.
 15. The spray foam insulationgun of claim 13 wherein said nozzle further comprises:a radiallyangularly extending resin ejection means for ejecting resin into saidfoaming agent-compressed air mixture.
 16. The spray foam insulation gunof claim 1, wherein:said resin nozzle includes a bore and a threadedcounterbore, and a resin ejected means for communicating said bore withan external surface of said nozzle.
 17. The spray foam insulation gun ofclaim 16 wherein:said means for communicating said second inlet borewith said resin nozzle includes a resin tube, one end of whichcommunicates with said second inlet bore, and the other end of whichengages said threaded counterbore of said resin nozzle; and said gunfurther includes a resin metering orifice insert, disposed within saidcounterbore of said nozzle between said resin tube and a shoulder formedby said bore and counterbore.
 18. The spray foam insulation gun of claim16, further comprising:a cylindrical extension communicating with adownstream end of said mixing chamber, said cylindrical extension beingconcentric with and radially spaced from said nozzle so that saidfoaming agent-compressed air mixture will exit the mixing chamberthrough an annular space between said cylindrical extension and saidnozzle, in a direction substantially parallel to a longitudinal axis ofsaid nozzle.
 19. The spray foam insulation gun of claim 1, wherein:saidmixing chamber includes a cylindrical outer body, one end of whichengages said valve housing.
 20. The spray foam insulation gun of claim19, further comprising:a concentric cylindrical extension of reduceddiameter communicating with the other end of said mixing chamber, saidcylindrical extension being concentric with and radially surroundingsaid nozzle.
 21. The spray foam insulation gun of claim 20, wherein:saidmeans for communicating said second inlet bore with said resin nozzleincludes a resin tube concentric with said cylindrical outer body, saidresin tube communicating said second inlet bore with an internal bore ofsaid resin nozzle.
 22. The spray foam insulation gun of claim 1, whereinsaid first valve means is further characterized as comprising:a tripleplug valve for simultaneously selectively connecting and disconnectingsaid first and third inlet bores to said mixing chamber, and said secondinlet bore to said resin nozzle.
 23. The spray foam insulation gun ofclaim 22, wherein said triple plug valve comprises:a cylindrical shaft,closely received in said transverse plug valve bore; and threesubstantially parallel bores through said cylindrical shaft,substantially perpendicular to a central axis of said shaft, said boresbeing oriented to coincide with said inlet bores of said valve body whensaid triple plug valve is in a first open position.
 24. The spray foaminsulation gun of claim 23 wherein said triple plug valve furthercomprises:annular seal grooves spaced along the length of saidcylindrical shaft, one of said grooves being disposed on either side ofeach of said bores through said shaft; and resilient seal means disposedin each of said annular grooves.
 25. The spray foam insulation gun ofclaim 23, wherein said triple plug valve further comprises:three annularseal grooves, disposed in the peripheral surface of said shaft and eachconcentric with an axis substantially perpendicular to a central axis ofeach of said three bores through said shaft, so that when said tripleplug valve is rotated through an angle of 90° from said first openposition, it is in a second closed position so that each of said annularseal grooves circumferentially engages one of said three inlet bores ofsaid valve housing to disconnect said bores from the mixing chamber andnozzle.